Zika Update: Adults Might Not be Safe Against Neurological Complications of Zika Virus

A new study involving mouse models revealed that Zika virus might not only affect neurological and cognitive health of infants, but also do some damage in the central nervous system of adults.

The study, published in the journal Cell Stem Cell, suggests that exposure to ZIka virus could also attack two areas in the adult human brain carrying immature brain cells, leading to brain damage that can cause epilepsy, personality changes, depression and dementia.

"Zika can clearly enter the brain of adults and can wreak havoc," explained Sujan Shresta, a professor at the La Jolla Institute of Allergy and Immunology and co-author of the study, in a press release. "But it's a complex disease-it's catastrophic for early brain development, yet the majority of adults who are infected with Zika rarely show detectable symptoms. Its effect on the adult brain may be more subtle, and now we know what to look for."

It is widely accepted that Zika virus attacks neural progenitor cells, the earliest form of neurons. This explains why infants are more susceptible in having complications due to Zika virus. As humans grow up, neural progenitor cells developed into fully-formed neurons. However, some areas of adult human brain retain niches of immature brain cells, which could be targeted by the virus.

For the study, the researchers mimic Zika infection in human adults using engineered mouse model. In the mouse model, the area of the brain that retained niches of neural progenitor cells are the subventricular zone of the anterior forebrain and the subgranular zone of the hippocampus. Both areas are vital for learning and memory.

Using fluorescent biomarkers, the researchers found out that Zika virus was not affecting the whole brain of their model. In infants, the dreaded virus attacked the whole brain, which explains the microcephaly. But in adults, the virus targeted the two areas in the brain with neural progenitor cells.

The researchers note that their study is still in its preliminary stage. More research is needed to fully understand long-term affect of Zika infection in human adults, which may appear to be asymptomatic.